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ARCADIS Ms.Amaru February 19, 2010 appropriate, an asphalt patch will be applied to restore the ground surface to prior conditions. Proposed Screening Levels Concentrations of tested analytes in soil will be compared to RWQCB, San Francisco Bay Region ESLs(RWQCB, 2008)for shallow soils with residential land use. Concentrations of analytes in groundwater will be compared to ESLs where groundwater is a current or potential source of drinking water. Additional Soil Removal The initial sampling results will be evaluated and compared to the ESLs as stated above, and the results will be discussed with the RWQCB, Central Valley Region. If the results are below the ESLs, the existing excavation area will be backfilled with clean material. If a statistically significant number of sample results exceed the ESLs, ARCADIS will mobilize to the site to expand the existing excavation and remove additional impacted soils. The intent of any expanded excavation will be to focus on removing impacted soil in the direction(s)of the borings containing concentrations above ESLs; however, structures, pipelines and/or conduits present near the excavation area may limit the ability to remove additional soil. If possible, additional soil will be removed using a backhoe or bobcat to approximately one foot beyond the impacted soil boring. If stained soil or elevated PID readings are present at one foot beyond the impacted soil boring, the excavation will be extended one additional foot. Soil excavation at or below the groundwater table is not planned. Excavated soil will be loaded into roll-off bins, and a maximum of 60 cubic yards is expected to be removed. Post-excavation confirmation soil samples will be collected directly from the excavation sidewalls and bottom using a properly decontaminated hand auger or trowel or, if conditions warrant, collected from the bucket of earthmoving equipment. One sidewall confirmation soil sample will be collected from the approximate midpoint of each of the four excavation sidewalls at depth intervals that correspond to areas exhibiting field indications of potential impact and/or at depths where previous samples indicated contaminants were present. One confirmation sample will also be collected from the bottom of the excavation area for a total of five samples. Sample locations and the number of samples collected may be adjusted in the field if Page: 5/7